This is carbon-filled PETG/Amphora. It makes visually appealing parts that print easily with (almost) my normal PETG settings. I used the .5mm stainless nozzle for lack of a hardened steel alternative on the M2.

What's striking is the matte texture right out of the printer and the pure black color. The surface texture masks layer boundaries and toolpath traces on top surfaces for an appealingly uniform, professional appearance. Mechanically, it seems to be quite stiff; a bit more than PLA perhaps and maybe about the same as ePC, but not as stiff as PC-Plus. It seems to print as easily as PETG.

With the excellent deep matte black, high stiffness and PETG-like glass transition temperature, I'm most looking forward to using this for optomechanical parts. It may also be the best material I have so far for printing large parts (larger than possible with PC's curling/shrinking problem) that are also very stiff and won't deform in a hot car.

It doesn't look like wood until you sand it, but when you do what you have is, for all intents and purposes, wood. The print quality pre-sanding is excellent and prints seem to be wood-like acoustically (tapping, thumping, etc). It sands well (expect sawdust!) and it takes stain and varnish well too.

Sanding is critical. I printed these concertina end pieces in the expected orientation (flat on the bed), but if I do this again I'll print them standing on edge so that the layer direction "creates" the wood grain. Thin layers are good (this was .15mm). Sanding all the toolpath marks out of the top surfaces of these pieces was labor intensive, and I attempted to keep the sanding marks all along one direction so as not to betray that its not real wood grain. Even so, notice that the best appearance is along the perimeter of the pieces where the layer alignment is consistent with the apparent grain. In these places especially I'm sure that even a seasoned woodworker would be fooled. It feels like wood too. Especially after rough sanding it's all fuzzy with sawdust.

Photos show the appearance fresh out of the printer, after sanding (60 grit), and after staining and rubbing on thinned varnish (1/3 Linseed oil, 1/3 mineral spirits, 1/3 varnish, 2 coats). Sanding was much easier along the perimeter where I was working with the layer direction, and more authentic too. Again, if doing this again I would print on edge. After the initial rough sanding I stained with a dark stain. After drying I sanded again with 220 grit to selectively remove the dark varnish to give the appearance of wood-like inhomogeneities, and then stained again with a lighter varnish. Of course the varnish doesn't penetrate like it does with real wood, so this kind of re-sanding to get the coloring right was easy. I overdid it with the 60 grit though, as some gouging is apparent.

Filament name: J260
Filament vendor: igus
Hotend used: V4 PTFE
Nozzle diameter: 0.35mm
Layer height: 0.2mm
Printing temperature: 270C / Bed=100C
Other information: igus is known for bearings. The funny thing for bearing material is that it feels rough and almost gritty, but it is rather hard. I had slight delamination, so I would recommend a higher print temperature, probably 280C.

This stuff is a little weird. As the extruder clears over free space, the filament is dense so it falls away from the nozzle and does not retain itself in a thread. You end up with a pile of poop on top of the Rambo case instead of a string hanging from the bed. (This might be because I print it on the high-side of PLA temperatures, though.)
It does print just like PLA, though. Printed objects are essentially very heavy, but quite brittle PLA.
Getting it to look like brass is the next step. I tried sanding, tumbling with brass .45 cases, scrubbing with Brasso, and a brass-bristled brush. The brush is most effective, as you can see from the photos.

Attachments

Various tries at polishing. One block and the right half of the ring have been brushed.